Trip-line system

ABSTRACT

The invention is a method and an apparatus for laying trip lines for sensing disturbances which are used to detonate explosive devices such as land mines. A controlled charge is used to generate a force in excess of that required to throw the trip line a predetermined distance and a stainless steel wire capable of substantial elongation without rupture is simultaneously used to dissipate such excess force.

er States atent [is] 3,673,963 McGowan July 4, 1972 [54] TRIP-LINE SYSTEM [56] References Cited [72] Inventor: Kenneth J. J. McGowan, Richmond, lnd. UNITED STATES PATENTS [73} Assigneez Avco Corporation Richmond Ind. 2,826,990 3/1958 Gross ..l02/8 [22] Filed: March 5, 1968 Primary Examiner-Samuel W. Engle Attorney-Charles M. Hogan [21] Appl. No.: 711,165

[57] ABSTRACT [52] US. Cl .102/38, 102/8, 102/89, The invention is a method and an apparatus for laying trip 89/1 G lines for sensing disturbances which are used to detonate ex- 51 1 1m. (:1 ..F42b 9/02, F42b 13/56 plosive devices Such as land A controlled charge iS used 58 Field of Search 102/1 38 s 9 89' 89/1 generate a fme in mess that required the triP line a predetermined distance and a stainless steel wire capable of substantial elongation without rupture is simultaneously used to dissipate such excess force.

2 Claims, 2 Drawing Figures PATEmEnJuL 4 m2 3.673.963

INVENTOR.

KENNETH J. J. McGOWAN BY May ATTORNEY.

TRIP-LINE SYSTEM In laying land mines or the like designed to be actuated by trip lines, it has previously been necessary to manually traverse an area within a given radius of the device to be tripped, and lay one or more wires radially thereof. The outer ends of these wires must then be anchored and the inner ends connected to the device. This required considerable manual effort, manipulation and time.

Arrangements for performing this task automatically have been suggested but have not been entirely satisfactory since they have required a line to be carried by a projectile ejected by an explosive charge in a cartridge or the like and such a charge either burns and weakens the line or breaks it. Moreover, it has not been possible to calculate exactly the amount of charge which would be sufficient to dispatch the end of the line the required distance and at the same time fully insure that the line will not break.

This invention permits a trip line, or lines, to be emplaced radially of a mine or similar device automatically, with certainty and precision and without breaking or injuring the line.

' The invention is illustrated in the accompanying drawings in which:

FIG. 1 is a longitudinal section of an exemplary cartridge adapted to house a trip-line-containing projectile; and

FIG. 2 is an elevational view of a projectile in flight just after it has been ejected from the cartridge.

Referring to FIG. I, a projectile designated generally as is loaded into a cartridge or case 11 which may be conveniently made of aluminum or aluminum alloy. It will be understood that the cartridge is designed to be loaded in any appropriate known launching device which is secured to or made integrally with an explosive device and arranged to be fired mechanically or electrically to launch the projectile 10 in a predetermined trajectory along some radius extending outwardly from the device.

One end of the cartridge 11 is closed by a sealing member such as a snap-on polyethylene cover 12 which at the time of firing is pushed away from the case, thereby permitting the projectile to begin its flight.

In the other end of the case is mounted a propellant arrangement comprising an azide coated bridge initiator 13 which is tired by a current through a center electrode 14. The center electrode is insulated at 15 from the remainder of the assembly and the voltage applied to this electrode will force a current through the azide coated bridge to its ground connection, namely, the case of the launcher.

When fired, the bridge initiator in turn ignites the propellant 16 which, by way of example in the illustrative combination, is fixed at 30 milligrams of A5 black powder. The propellant ruptures the initiator enclosure and generates propellant pressure on a buffer 17 which may be made of cardboard and is inserted to protect the wire trip line 18 from flash burns. It will be readily visualized that the pressure resulting from the expanding propellant will force the projectile out of the case and initiate its flight. During its flight it will emplace the trip line which is attached to both the case and to the projectile.

Referring now to the projectile, its principal component is the trip line 18 which must be of high tensile strength and be capable of elongation under tension by as much as 50 percent of its length before it will rupture. An example is Type 304 stainless steel wire 5 mils in diameter, and such a wire is, according to the invention, carefully and accurately wound on a brass spool 19 with its distal end securely tied to the projectile body at 20. The spool is formed with a nose and a tail. Another component is the line guide 21 which tapers at its rear serves to provide a balanced center exit port for the wire, thus stabilizing the flight of the projectile.

An anchor 22 of hardened spring steel surrounds the spool l9 and is compressed within the cartridge 1 l in such a manner that the spring times 23 are folded tightly or biased inwardly against the line guide 21. The anchor is securely fastened to the spool by means of a conventional steel drive screw 24. The anchor, when released from the case, will assume the fan-like configuration shown in FIG. 2.

e ordnance device which utilizes the trip-line launcher described herein will be arranged to utilize a number of these devices, for example, six, in order to provide coverage of the terrain in several directions radially of the device. After the projectile has been fired, the anchor times will expand and thus provide an anchor which will attach itself to any irregularities in terrain and vegetation so that it will resist movement when a pull is exerted on the trip wire. Subsequently, any disturbance to the trip wire will result in a pull or force being exerted on the case 11 to which it is anchored. This force can be utilized to effect the closure of an appropriate contact connected into the firing circuit of the device to cause detonation thereof. The switch or contact and related circuit elements which perform this function are well known in the art and are not, in and of themselves, a part of the present invention.

An important feature of the invention is the means and method whereby the possibility of wire breakage is avoided by controlling the amount of propellant (and therefore the propellant force on the projectile) and conjointly therewith providing a trip line of high tensile strength which is capable of substantial elongation under tension without breaking. Any excess force over and above the exact amount of propellant required to propel the projectile over its designed trajectory is thus dissipated in the deformation of the wire, thereby avoiding the danger of breakage. The desired distance to be covered by the trip line may, by way of example, be 20 to 30 feet, but it should be borne in mind that the area covered by the trip wire should not exceed the effective area of the explosive device.

Having thus described my invention, I claim:

1. In combination with a cylindrical cartridge formed with an open end and a rear end and adapted to be closed by an initiator,

and an initiator mounted in said rear end, a projectile adapted .to be loaded therein and launched therefrom comprising:

a spool extending axially in the direction of flight having a nose and a tail,

a coaxial line guide secured to the nose of said spool and fonned to extend axially beyond said tail, said line guide tapering at its rear to form an exit port,

anchor means secured to said nose,

an extensible stainless steel wire trip line, capable of elongation under tension, coiled between said nose and tail, one end of said wire being connected to said spool and the other end of said wire extending through said exit port and being connected to said cartridge, said line being adapted and arranged to unwind during flight of said spool, and

said initiator producing a force in excess of that necessary to project the spool to such a distance as to fully extend said trip line wire.

2. The combination in accordance with claim 1 in which the anchor means further comprises fan-like spring tines which are biased inwardly and folded against the line guide when said projectile is loaded in the cartridge wherein when said projectile is launched from said cartridge said tines spring outwardly from the line guide and thus provide an anchor which will attach to any irregularities in terrain and vegetation whereby the projectile will resist movement when a pull is exerted on said trip wire.

i 19! t t 

1. In combination with a cylindrical cartridge formed with an open end and a rear end and adapted to be closed by an initiator, and an initiator mounted in said rear end, a projectile adapted to be loaded therein and launched therefrom comprising: a spool extending axially in the direction of flight having a nose and a tail, a coaxial line guide secured to the nose of said spool and formed to extend axially beyond said tail, said line guide tapering at its rear to form an exit port, anchor means secured to said nose, an extensible stainless steel wire trip line, capable of elongation under tension, coiled between said nose and tail, one end of said wire being connected to said spool and the other end of said wire extending through said exit port and being connected to said cartridge, said line being adapted and arranged to unwind during flight of said spool, and said initiator producing a force in excess of that necessary to project the spool to such a distance as to fully extend said trip line wire.
 2. The combination in accordance with claim 1 in which the anchor means furtHer comprises fan-like spring tines which are biased inwardly and folded against the line guide when said projectile is loaded in the cartridge wherein when said projectile is launched from said cartridge said tines spring outwardly from the line guide and thus provide an anchor which will attach to any irregularities in terrain and vegetation whereby the projectile will resist movement when a pull is exerted on said trip wire. 